Chapter 74 - External Noise Distinguishes Mechanisms of Attention

Abstract

Attention to objects or features of objects affects performance on perceptual tasks, such as detection, recognition, or identification. The speed or accuracy of task performance can be significantly influenced by changes in the state of attention, especially in complex task environments. The state of attention may be manipulated by specific environmental cues, or by decisions about allocation of attention induced by task demands. The challenge is to understand and predict these attention-mediated changes in task performance, and to identify the mechanisms by that attention is operating. A theoretical and empirical framework has been developed to directly assess the mechanisms of attention by systematically manipulating the amount and/or characteristics of the external noise added to the signal stimuli and measuring modulations of perceptual discriminability (signal and noise levels) in the cognitive processes. Three classes of attention mechanisms—stimulus enhancement, external noise exclusion, and internal noise reduction, each with its signature performance pattern, can be distinguished. Empirically, the two mechanisms of stimulus enhancement and external noise exclusion are shown to occur in different circumstances. A task-taxonomy of attention mechanisms is obtained by partitioning experiments in the literature according to several factors. The framework has also been extended to the assessment of spatial and temporal characteristics of the attention window, the coordination of multimodal auditory-visual cues in the performance of visual tasks, and the action of multi-task load in performance.